rob can dig 1/10ft in one hour
Shayna can dig 1/7ft in one our
together they can dig
1/10+1/7
(7+10)/70 in one hour
17/70
in for hours they can dig
17/70×4
68/70
the left work is 2/70
in 60 minutes they can dig 17/70
1/70 work can be done in 60 minutes/17
2/70 work can be done in 60/17×2 minutes
7.088 minutes
for the entire work they take 4hours and 7 minutes
The expected completion time is μ = 40 weeks.
The random variable, X = 38 weeks (the probable time)
If the standard deviation is σ, then the z-score is z = (x - μ)/σ.
Let us test the given standard deviations.
When σ=1,
z = (38-40)/1 = -2
From standard tables,
P(x<=38) = P(z<=-2) = 0.0228 =2.3%
When σ=2,
z = (38*40)/2 = -1
P(x<=38) = P(z<=-1) = 0.1587 = 15.9%
When σ=4,
z = (38-40)/4 = -0.5
P(x<=38) = P(z<=-0.5) = 0.3085 = 30.9%
Answers:
z=1 => 2.3%
z=2 => 16% (approx)
z=4 => 31% (approx)
Answer:
A and C
Step-by-step explanation:
This would be the correct answers because they are congruent and dilated from each other
